In this study, 449 patients, included between October 2004 and October 2012, were sorted into three groups according to diabetic nephropathy stages: without (persistent normoalbuminuria, n=248), incipient (microalbuminuria, n=82) and overt diabetic nephropathy (macroalbuminuria or proteinuria or renal replacement therapy, n=119). Measurements of urinary albumin-to-creatinine ratio (ACR) or urinary albumin excretion rate (UAER) were used to define DN: patients with persistent normoalbuminuria (<30 mg/g creatinine or <20 μg/min) were classified as without DN (n=248); patients presenting persistent microalbuminuria (30-300 mg/g creatinine or 20-200 μg/min) were classified as having incipient DN (n=82); and patients presenting persistent macroalbuminuria (>300 mg/g creatinine or >200 µg/min), proteinuria (>500 mg/24 h) or renal replacement therapy were classified as having overt DN (n=119). Genotyping of polymorphisms was performed by Real Time PCR using fluorescent -labelled probes.